Technical Field
The present disclosure relates generally to user interaction with an electronic device having a touch screen display, and a more specifically to precision selection of items and/or points using an electronic device having a touch screen display.
Background Information
Touch screen displays are becoming increasingly common on a variety of types of electronic devices. For example, most mobile devices (e.g., smartphones, tablet computers, etc.) employ some form of touch screen display, and use touch input as their primary mode of user input. By its very nature, touch input may be quick and intuitive, making it well suited for many types of applications. However, for some types of applications, touch input may be less than ideal. In its native form, touch input often lacks the level of detail and precision provided by traditional keyboard and mouse based input. A high level of detail and precision may be important to some applications, for example, to computer aided design (CAD) applications, where a user may be called upon to discriminate between nearby items or points, to select a desired one.
The lack of detail and precision in touch based input stems from a variety of sources. One source is the reduced number of input types that are possible with touch based input, as compared to keyboard and mouse based input. With a keyboard and mouse, a user may enter a large number of distinct types of input, using the movement sensor of the mouse, the various buttons on the mouse, the scroll wheel of the mouse, and the various keys of the keyboard, alone, or in combinations. Each of these distinct types of input can be directly mapped to types of actions in an application. However, with touch based input, a user generally has fewer types of input they may enter, being limited to movements recognized on the touch screen display. For example, while a user may tap, hold, pinch, drag, swipe, etc., on the touch screen display, there are a fairly limited number of different things the user can do. This may pose a problem when designing a user interface for an application. While a designer may desire to directly map a variety of actions supported by the application to distinct types of input, there may simply be more actions than input types.
Another source of the lack of detail and precision stems from the typical lack of persistent position tracking on touch screen displays. With a typical keyboard and mouse based user interface, a cursor is persistently displayed to designate a position. Even if the user is not moving the mouse, the cursor is still shown, and its lingering presence can be used to trigger actions. For example, a “hover over” may be detected, where the cursor is maintained over an object for a short period of time. This may trigger an action (e.g., displaying information, such as a “tool tip”, about the object). However, this type of interaction is typically not available on touch screen displays. Traditionally, on touch screen displays, position is only designated momentarily, when a user touches the screen. As such, interactions such as “hover overs” are generally not enabled.
Still another source of the lack of detail and precision stems from ambiguity in position designation on touch screen displays. With a mouse, a user can generally select a single pixel in a user interface. A user can see the cursor, and move it to exactly where they desire, making tiny adjustments as needed. However, with a touch screen display, this type of operation is generally not possible. When a user touches the screen, their finger (or the stylus, if one is used) typically obscures their view of the position they are trying to designate. The position is somewhere under their finger (or the stylus tip), but the user cannot generally see where. Further, the entire area of contact is generally registered as being touched, rather than a distinct point. Algorithms must be employed to try to guess where in this area the user really intended to designate. Given this guesswork, when items or points are close together, a user may have to repeatedly touch the display screen, until they happen upon the desired result.
Accordingly, there is a need for improved techniques for selection of items and/or points using a touch-screen display. While this need may be applicable to a variety of types of applications executing on electronic devices (e.g., mobile devices), it may be particularly acute for CAD applications executing on mobile devices.